Cement composition



CROSS REEEREt-QE manta United States Patent 3,118,779 CEMENT COMPOSITIONBernard S. Leonard, Arlington, Va., assignor to Sohdrte Corporation, acorporation of the District of Columbia When it is desired to use thecomposition for patching Patented Jan. 21, 1964 ice cracks, sealingleaks or repairing breaks in walls, steps, sidewalks, or even boat hullswhile they are in water, the surface is first prepared in the usualmanner, i.e., it is scraped or brushed clean, cracks or holes arewidened by No Drawing. Filed June 9 1961, Ser. No. 115,942 groutingtools or otherwise, to facilitate application of the 1 Chink (CL 93mixture and then the mixture of the dry solids is blended with as littlewater as is necessary, about one part of E This nti relates to ymixtures Possessing an water to three parts of dry solids usually beingrequired ability to set to a hard, strong product either underto producea stiff mix suitable for appliqatigr water or in the atmosphere. Moreparticularly, it relates 10 The preferred mode of application is todampen the t0 compositions Comprising high early Strength t a cleanareas with a sponge or brush and to apply the stiff cement and aParticular grade of-snica Sand p portioned mixture immediatelythereafter to the dampened area with so as to set into a product whichis not penetrated by a trowel or other tool, and to then permit themixture water and does not absorb water approximately four to et or h dminutes after it has been mixed with a suitable amount The mixt ill et ta h rd trong product even of water and to the further improvement insuch comunder water. One possible reason for this is that once itpositions, conferred by the addition of suitable proporis formed, themixture does not appear to absorb any tions of sodium bicarbonatethereto. water shortly after the original addition of water to form r ie fi the com ositions constituting this invention the original stiffmixture. When running leaks are to be compr sg d ry mixtupe s gg nsistipu g ype li-l portm repaired or the mixture is to be applied underwater, a walk a high early strength grade defined 1n the delay of 2-3minutes between completion of mixing with A.S.T.M. Standards underA.S.T.M. designation No. 0- water and application of the Wet mixture tothe under 150-56, plus No. 1 silica sand, a white sand of substan waterarea is desirable so as to permit the mixture to ttially unif g gn cgewand grain size, 98.4% of which is acquire its imperviousness topenetration by water. Then retained on a No. 100 mesh screen and 1.7 ofwhich is the stiff mix is forced into place with the hand or by retainedon a No. mesh screen, and containing, as an mechanical means and is heldin place for another 2 to 3 optional constituent, a relatively small butnevertheless minutes after which the hand or applicator is withdrawn,important amount of sodium bicarbonate. leaving the patch as a waterresistant body.

Said mixture is conveniently formed by merely blending Representativesamples of a 2:1 (cementzsand) mixture the dry ingredients in a batchmixer of adequate size, in 30 containing 8 parts of sodium bicarbonatefor each 150 the following relative proportions: parts of cement plussand by weight, set to a compressive Parts by weight strength of 2250pounds per square inch when permitted ype III Portland cement 4-5 to dryin air for 48 hours. No, 1 silica sand 2 In addition to the foregoinguses, it has been found j- Nail-{C0 1 2.5 6% that the compositionsformed by the addition of water to 1 Based on the total of cement plussum 1 the mixtures described will adhere to hard solids, such as d t tobe critical it rock, stone, cement, marble and the like, to metals suchwhlle the proportions appea? as llOIl and steel, and to wood and otherporous" matehas been found that enriching the mixture beyond 2.5 rialsParts of cemeni per 1 part of Sand.by weilght resullts The foregoingdescription is illustrative of a preferred P a product.whlch crumiflesand.that mcreasmg the re mode of practicing the invention which is notintended tlve proportion of sand in the mixture very much above to belimited except as required by the appended Claim. one part of sand foreach two parts of cement yields prod- I claim: which do not possess theProperty of being able to A dry mixture consisting of between 4 and 5parts by dry qulcklypnder weight of Type III Portland cement, 2 parts byweight relatw? proportions of blcarbqnate may not of No. 1 silica sandand between 2.5% and 6% by weight varhed appreclably from therange.speclfied' when pres of sodium bicarbonate, based on the total ofcement plus ent in amounts below 2.5%, the bicarbonate produces no Sandnoticeable acceleration of the time required for the cement-sand mixtureto set, especially under water. At the other end of the range, it hasbeen found that amounts of References C'ted the file of this Patentbicarbonate above 6% are detrimental, particularly where UNITED STATESPATENTS the mixture is used in locations not immersed in water.

In these instances the excess of bicarbonate soon comes to 3'675wesirmayr 1869 the surface as a noticeable powdery white deposit which 5224O744 May 1941 may mar the appearance of the patched area. 2597370Peckmfm May 20, 1952 Once a suitably proportioned dry mixture has beenpre- 2,836,502 Bartok et a1 May 1958 pared, it may be stored in jars,cans, or other sealed containers for extended intervals of time, untilit is desired OTHER REFERENCES to use the mixture. 0 Lea and Desch: TheChemistry of Cement and Concrete, Edward Arnold Publishers, 1956, pp.468-469.

